\(\dfrac{3}{4}=\dfrac{3\times5}{4\times5}=\dfrac{15}{20}\)

\(\dfrac{2}{4}=\dfrac{2\times5}{4\times5}=\dfrac{10}{20}\)

\(1=\dfrac{20}{20}\)

\(\dfrac{6}{5}=\dfrac{6\times4}{5\times4}=\dfrac{24}{20}\)

Vì \(\dfrac{10}{20}< \dfrac{15}{20}< \dfrac{20}{20}< \dfrac{24}{20}\) nên \(\dfrac{2}{4}< \dfrac{3}{4}< 1< \dfrac{6}{5}\)

B

\(3\dfrac{1}{5}=\dfrac{16}{5}\)

\(50\%của16=16\times50\%=8\)

\(112\times3,8=425,6\)

\(0,8=\dfrac{8}{10}=\dfrac{4}{5}\)

Ta có: \(m< n\)

\(\Rightarrow2m< 2n\)

\(\Rightarrow-8+2m< -8+2n\)

a, 2 x 1 = 2

    5 x 1 = 5

b, 5 : 5 = 1

    2 : 2 = 1

\(\dfrac{AB}{CD}=\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{AB}{10}=\dfrac{2}{3}\)

\(\Leftrightarrow3AB=10.2\)

\(\Leftrightarrow AB=\dfrac{20}{3}\left(cm\right)\)

\(\Rightarrow\) Không có đáp án thỏa mãn.